Unfortunately, depending on your other income, a portion of your social security benefits may be taxable.
The portion of your Social Security Benefits that are taxable is based on your Modified Adjusted Gross Income (MAGI).
Check out IRS Pub 915, Page 7, to view the Worksheet used to determine the taxable amount of your Social Security Benefits.
You can also find more information in the TurboTax FAQ below:
https://ttlc.intuit.com/replies/3299920